桑迪亚国家实验室是由桑迪亚公司是洛克希德·马丁公司，根据合同DE-AC04-94-AL85000经营的国家核安全管理局的多方案实验室。单调查小组研究项目（批准号：DE-SC0002619）Violi教授（美国密西根大学安娜堡分校）下的工作还得到了美国能源部基础能源科学办公室。韩元是由美国能源部科学办公室，在能源合同号DE-AC02-05CH11231美系早期职业研究计划的支持。先进光源是由处长能源的合同号DE-AC02-05CH11231美系，科学，基础能源科学办公室的办公室，支持。竹脚妇幼医院承认继续支持这项研究由东风集团根据合同KO 1363/18-3的一部分。

1，气相中的实验<ol><li>点燃低压预混火焰<ol><li>确保冷却水流动通过燃烧器和火焰室壁和该火焰室抽至〜0.1毫巴。 </li><li>通过燃烧器表面建立的氩气的1升/分钟流量和氧的1.5升/分流量，并保持80毫巴（6​​0托）在火焰室内的压力。 </li><li>定位热线点火器在燃烧器表面;设置氢气流至0.4升/分钟，并且迅速激活点火器。 </li><li>点火后，关闭热丝点火器，并从燃烧器重新定位它拿走。 </li><li>建立氩气，氧气，氢气和燃料的所需流量。调节压力以匹配目标火焰[一般为20-40毫巴（15-30乇）]的条件。注：在原文献中提供火焰条件个人火焰。例如，对于流动化学计量丙二烯和丙炔火焰是在Hansen 等 22家上市。 </li></ol></li><li>收购光电离效率（PIE）曲线 - 能量扫描<ol><li>当在电离室中的压力是≤10 -6毫巴，将电压施加到飞行时间的质谱和微通道板检测器的离子光学元件，并打开束线阀。注意：早期校准实验（在视频中未示出）被用来找到电压设置用于质谱仪的最佳性能。 </li><li>启动Labview数据采集程序“一般Interface.vi”（ 图2）和燃烧器移动到使用该软件的“电机”选项卡中所需的位置。注：本LabVIEW代码是在光束线开发，可根据要求提供。 </li><li>使用“常规”选项卡来定义扫描参数， 即每个光子的能量EV步数。通常情况下，为0.05电子伏特的步长是使用。 </li><li>使用“ALS”选项卡中的光子能量设置为所需的初始值，并定义了“ALS能源”为“主动”。 </li><li>在“控制”面板中，激活“K6485”读出由光电二极管测量的光电流。 </li><li>在“P7886”选项卡上，使用“设置参数”按钮来设置扫描的次数（通常为2 19和2 21），箱（通常48K）的数量，和箱宽（500皮秒）。 </li><li>输入一个有效的文件路径和名称，然后单击“开始”来启动计算机控制数据采集过程。 </li></ol></li><li>收购质谱研究 - 燃烧器扫描<ol><li>适用的电压作为能量扫描以飞行时间的质谱和微通道板检测器的离子光学器件。 </li><li>打开阀门束线，以允许在腔室中的光子束。 </li><li>打开Labview数据ACQuisition程序“一般Interface.vi”。 </li><li>在软件中使用“汽车”选项卡上，使用“慢跑”移动燃烧器表面尽可能接近采样锥，并定义该位置为“起源”。定义电机是“有效的”。 </li><li>使用“常规”选项卡来定义扫描参数， 即每燃烧运动毫米的步数。典型值是0-5毫米的20个步骤，5〜20毫米的15个步骤，和20-30毫米的5个步骤。 </li><li>使用“ALS”标签，光子的能量设置为所需的值。典型值是8-16.65电子伏特。 </li><li>在“控制”面板中，激活“K6485”读出由光电二极管测量的光电流。 </li><li>在“P7886”选项卡上，使用“设置参数”按钮，启动一个子VI（ 图3）来设置扫描的次数， 即质谱ADDE数d于彼此的顶部在每个燃烧器的位置（一般为2至19和2 21），箱（通常为48,000）的数目，和bin宽度（500皮秒）。 </li><li>提供一个有效的文件路径和名称，然后单击“开始”，开始自动数据采集过程。 </li></ol></li></ol><img alt="图2" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig2highres.jpg" width="500" /> 图2中的数据采集程序的图形用户界面。 <a href="https://www.jove.com/files/ftp_upload/51369/51369fig2highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig3highres.jpg" width="500" /> 图3。图形用户interface来输入多通道定标器参数。 <a href="https://www.jove.com/files/ftp_upload/51369/51369fig3highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 2，气溶胶实验<ol><li>点燃近大气压反对流火焰<ol><li>确保冷却水流经燃烧器，该反应物出口是约。间隔10mm，并且该火焰室抽至最低可达到的压力（〜2毫巴）。 </li><li>填写火焰室氩气并带来高达约860毫巴（6​​50托）的压力。 </li><li>将点火线圈左右。在这两个燃烧器出口的中心。 </li><li>设置气体流量如下（AR应该已经流，因为它是用来填补室）：氧化剂流：O 2 0.3升/分钟和Ar 1.6升/分钟;氧化剂流伴流：氩气2.5升/分钟;燃料流：H 2 0.3升/分钟，氩气2.5升/分钟;燃料流伴流：氩2.5升/分。 </li><li>打开氢气和氧气的阀门，并立即对点火线圈切换。 </li><li>一旦火焰被点燃，关闭点火线圈，并收回它。 </li><li>建立氧气，氩气和燃料的所需流量。关掉氢气的流量，并且设置压力和反应物的出口分离到所需的值，目标火焰。注意：在斯基恩等 4所提供的流动速率为丙烷火焰，这是显示在视频。 </li></ol></li><li>采集的气溶胶质谱的<ol><li>应用适当的电压，以离子光学元件和AMS的检测器。注意：发现在早期校准实验，这未在视频中所示的电压设定为一个最佳的性能。 </li><li>打开Labview数据采集程序“通用接口 - 反对 - Flow.vi”。注意：此VI是“常规Interface.vi”，其中电动机控制已经更新到的变形配合新的需求。 </li><li>使用“电机”标签上的“慢跑”应用到翻译的相对流动的燃烧器，以使石英探针是在最接近的燃料流出口（ 图4）的位置。而在这个位置上，复位电机步进位置为零。这个程序定义了“原点”位置。 </li><li>慢慢打开四分之一圈球阀允许油液从火焰采样线进入空气动力学镜头（ADL）的系统。确认在ADL的出口处的压力是接近1×10 2毫巴。 </li><li>使用“常规”选项卡来定义扫描参数， 即每燃烧运动（燃烧器扫描）或光子能量（能量扫描）的毫米步数。 </li><li>使用“ALS”选项卡中，设置所需的光子能量，并使用“汽车”标签燃烧器移动到所需的燃烧器位置。 </li><li>使用“P7886”选项卡，在“中将Parameters“按钮，在其中可以设置采集参数。 </li><li>定义“电机”（燃烧器扫描）或“ALS能源”（能量扫描）是“积极的”。 </li><li>插入一个有效的文件路径和名称在相应的字段，并单击“开始”。气溶胶质谱现在会自动拍摄。 </li></ol></li></ol><img alt="图4" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig4highres.jpg" width="500" /> 图4。用于燃烧器运动的相对流动的火焰组装的图形用户界面。 <a href="https://www.jove.com/files/ftp_upload/51369/51369fig4highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enols+are+common+intermediates+in+hydrocarbon+oxidation.">Enols are common intermediates in hydrocarbon oxidation.</a> Science. 308, 1887-1889 (2005).</li><li>Tolocka, M. P., Zhao, B., Wang, H., Johnston, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+species+associated+with+the+early+stage+of+soot+growth+in+a+laminar+premixed+ethylene-oxygen-argon+flame.">Chemical species associated with the early stage of soot growth in a laminar premixed ethylene-oxygen-argon flame.</a> Combustion and Flame. 142, 364-373 (2005).</li></ol>

作者什么都没有透露。

的阻燃采样和基于同步加速器的真空紫外单光子电离质谱所描述的组合提供最详细的直视的实验室为基础的模型火焰目前可能的化学组成。质谱仪提供的所有采样火焰物种的通用检测同时具有高灵敏度（ppm范围内）在很宽的动态范围。纯对这一技术的成功是利用同步加速器产生的VUV光子，其能量可以很容易地被调整，以提供异构体和碎片的控制之间的良好的选择性。分析复杂混合物时，后者的因素是很重要的。所描述的实验的功能是通过气相色谱法，这是常用的异构体分离，并通过使用高能电子电离常规技术所无法比拟的。源于这一事实，特别是对于较大的质荷比，毫安同步加速器为基础的技术的局限性NY不同的异构体是可以想象的，然后不能被唯一标识，而他们的贡献不能可靠1分离。实验结果显示，在异构体分辨火焰的组合物的形式，可产生燃烧的化学改进的动力学模型在一个非常详细的分子水平。 所描述的实验是非常复杂和故障排除程序的描述是超出了可记录在视频和/或本手稿的协议部分。这个事实也是真实的数据分析程序。修改该实验装置在所分配的“beamtime”之间，通常离线进行。由于这些实验的重点是定量测定燃烧中间体，这是非常关键的是具有稳定的和可重复的火焰。此外，有必要明智地选择了光子能量与其他扫描参数，以获得一个Ñ​​充分组实验数据是足够可靠的测定火焰结构的。 在先进光源进行火焰实验已成功地协助解开苯形成的化学反应在碳氢化合物火焰7。的共振稳定基团作为前体的突出作用已经建立，例如，与炔丙基，烯丙基的识别，和i-C 4 H 5的基团。 因为苯的形成被认为是仅在整体烟灰的形成过程中的第一步，更多的努力正在进行的先进光源来识别火焰取样烟尘颗粒的化学组成。相比于以前的类似煤烟采样实验28，这个新成立的气溶胶取样试验允许用于记录近阈质谱，这意味着光子的能量可以被精确调谐吨Ø仅略高于组件的电离能，从而避免碎片。此外，碎裂也很大程度上避免了通过采用闪蒸气化过程中的温度控制的铜块上。然而，本实验目前由不能够提供定量数据的限制。此外，记录的质谱不特定的粒子，但平均在许多颗粒可能在不同的组成和规模。此外，冷凝可以而且确实发生在取样探头，与火焰微粒伴生物种的鉴定复杂。此外，检测出的物种必须是挥发性足以在铜块（300-400℃）在真空条件下的温度被蒸发。然而，早期的定性数据表明，煤烟的前体物质的组合物是依赖于燃料的化学结构和烟灰前体的形成机理是动力学驱动的，而不是THERmodynamically。气溶胶质谱仪的努力，现正处于早期阶段，所获得的见解迄今为止发掘更多的研究机会。 对烟灰的形成过程今后的工作很有可能把重点放在化学超越第一芳香环， 即 ，茚，萘，蒽等，以及它们的同分异构体的形成。最终的目标是要了解的粒子开始时化学（和物理），并制定一个预测模型，能够描述整个烟灰形成过程（从燃料氧化颗粒凝）。

建立一个一致的和预测机制的分子增长和烟灰的形成过程是在燃烧化学研究8,9的最大挑战之一。燃烧过程中占一半以上的微粒空气污染（PM 2.5 -由≤2.5μm的空气动力学直径定义的微粒），并且，为了减少这些不希望的燃烧副产物的排放量，重要的是要知道他们的身份，浓度，并形成通路10。燃烧副产物的性质是由燃料和下它被烧毁的条件的影响。许多研究已发现，燃烧排放到严重的环境和健康影响11-13。例如，燃烧产生的微粒对空气质量，大气能见度和地球大气的辐射平衡有很大的影响。据推测，在空气中的梳状的化学组成燃烧室产生的微粒决定了其毒性，这是常见的多环芳香烃（PAHs）相关联。后者物种被认为是烟灰的分子前体，并且它们形成在不完全燃烧过程。再次，以确定这些过程仍然是一个具有挑战性的问题。 一般来说，燃烧反应，这是在这些排放的起源，遵循复杂的燃料分解和氧化途径，涉及许多不同的反应性物种。他们在数百反应的速率依赖于温度和压力14,15甚至上千的网络连接。 层流，预混，燃烧稳定的火焰持平，可在压力低至20-80毫巴（15-60乇）成立，代表常用来解开这个复杂的化工网调查污染物的标准燃烧环境之一的潜力y所典型的燃料16。在这种结构中，燃料和氧化剂时，它们到达火焰前缘已经混合;因此，燃烧的速率是通过化学过程，而不是通过混合占主导地位。通过在低于大气压的压力下操作这些火焰，将反应区域的物理厚度增加时，允许的温度和浓度梯度以激光为基础的或探头采样技术1,17改进的空间分辨率。 为了精确地分析这种火焰的化学组成，一种分析工具是必需的，它提供所有种类的通用检测同时，高灵敏度和动态范围，同分异构体之间具有良好的选择性和分子碎片的控制。在燃烧化学研究的一个突破，配合使用阻燃采样质谱在同步加速器光源的地方可调谐的真空紫外（VUV）辐射是用于近THRE实现shold单光子电离5,6。在火焰的实验在劳伦斯伯克利国家实验室，这是显示在影随行的先进光源（ALS），气体样品从预混火焰中由石英锥形撤回，扩展到更高的真空，并通过真空紫外光电离1,5的光子。该实验装置示意性地显示在图1中，关键这个实验的成功是在适当的范围的能力来调整电离的光子的能量，以减少或什至避免光裂解，并允许特异性异构体1,3 ，5,18。如图所示，在视频，光电离效率（PIE）曲线可以通过调整光子能量19，这使我们能够识别复杂的火焰混合特定的异构体的物种被记录下来。在PIE曲线个别品种一般都有明显的特征， 即电离阈值，形状和强度。视频一LSO示出用于确定各个组分的摩尔分数分布，以在燃烧器表面的距离的函数的实验方法。 这些ALS基燃烧实验已经集中在碳氢化合物火焰烟灰的形成过程和含氧的下一代，生物衍生燃料1,20的氧化。与问候的烟灰形成的问题，该实验揭示了许多新的见解。总之，现在理解的是，燃料的化学结构影响母体分子的身份（和数量），并且因此许多不同的途径可以向整体烟灰形成过程7,21的第一步骤。 甚至更深入地了解了烟灰形成的化学识别火焰产生的烟尘纳米颗粒与ALS型气溶胶质谱仪的化学成分进行时获得。在这个新的实验，这为explained在视频的第二个一半，非预混（扩散）的火焰被使用。实验装置中还示出在图1中，在这种配置中，火焰被建立在接近大气压的压力[933毫巴（700托）]的燃料和氧化剂的两个相对的层流射流之间。因为燃料和氧化剂流保持反应区外分离，这种配置提供了一个很好的机会，研究分子生长过程。火焰产生的粒子是从使用的石英微探针火焰撤回，然后专注与气动镜头系统到加热的铜靶，那里的颗粒闪烁蒸发，分解成其各个组成成分。这些分子构建模块，然后由从ALS的VUV光子电离，以及相应的离子质量选择的4。不是所有必要的工作可以显示在视频，但该气溶胶的数据表明，烟灰的形成机制可能kineticall<html> y和不热力学控制。此外，数据还表明，被广泛接受的夺氢-C 2 H 2 -加成由H-抽象和C 2的一个重复序列（HACA）机制，在这种小的芳族物种生长到较大 ​​的多环芳香烃（PAHs） H 2 -加成反应，不能解释所有观察到的粒子成分。 结合视频，下面的协议详细说明了数据采集程序。 <img alt="图1" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig1highres.jpg" width="500" /> 图1：火焰采样分子束和气溶胶质谱实验在劳伦斯伯克利国家实验室的先进光源的示意图。自文献的权限。 2和4。9fig1highres.jpg“目标=”_blank“&gt;请点击这里查看该图的放大版本。

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	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Name of Material/ Equipment</td>
			<td style="width:71px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">flame-sampling mass spectrometer</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>custom-built</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">aerosol mass spectrometer</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>custom-built</td>
		</tr>
	</tbody>
</table>

flame experiments at the advanced light source: new insights into soot formation processes

下面的实验方案和影随行所关注的，它们在先进光源的化学动力学光束线的劳伦斯伯克利国家实验室1-4（ALS）进行火焰实验。本视频演示了如何以实验室为基础的模型火焰复杂的化学结构，采用阻燃采样质谱与可调同步加速器产生的真空紫外（VUV）辐射进行了分析。这种实验方法结合异构体分辨能力，具有高灵敏度和大动态范围5,6。视频的第一部分介绍了涉及燃烧稳定，减压（20-80毫巴）层流预混火焰的实验。一个小的烃类燃料是用于所选择的火焰来演示的一般实验方法。它示出物种的配置文件是如何从燃烧器表面获取的作为距离的函数，以及如何在VUV的可调谐性光子的能量被用于有利地，以确定基于其电离能多燃烧中间体。例如，这种技术已经被用于研究烟灰形成过程的气相方面和视频显示了共振稳定基团，如C 3 H 3，C 3 H 5，和i-C 4 H 5，被确定为重要中间体7。这项工作一直集中在烟灰形成过程，并从化学角度来看，因为包含上百万个碳原子的化学结构从燃料分子具有在短短毫秒只有几个碳原子组装这个过程是非常有趣的。在视频的第二部分突出了新的实验，在其中一个对置的流扩散火焰和基于同步加速器的气溶胶质谱法用于研究燃烧产生的烟灰粒子4的化学组成。实验结果表明吨帽子被广泛接受的H-抽象-C 2 H 2加成（HACA）机制不负责观察到大量多环芳香烃（PAHs）的形成唯一的分子生长过程。

从低压预混燃烧器火焰采样气体的典型的质谱示于图5。的物种造成的信号的同一性通过火焰取样光电离效率（PIE）曲线为每个质揭示荷比（m / z）的比例和他们相比，已知的异构体特异性电离能和PIE曲线。的火焰采样PIE曲线的典型例子示于图6中为M / Z = 39（C 3 H 3）和41（C 3 H 5）。数据取自的化学计量丙炔焰22。该信号由它们的特征电离阈值清楚地识别从共振稳定化炔丙基和烯丙基基团来发起。对于许多m / z值，多个异构体经常发现通过观察多个阈值。许多例子已经在文献中广泛地进行了讨论，例如，M / Z= 40（丙二烯和丙炔），44（乙烯醇，乙醛），54（1,3 -丁二烯，1 -丁炔，2 -丁炔中），或78（富烯和苯）23-27。 <img alt="图5" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig5highres.jpg" width="500" /> 图5。飞行时间的质谱。在从化学计量丙炔氧焰的低压预混燃烧器1.25毫米距离记录为9.9电子伏特的光子。所有峰可以容易地分配到各燃烧中间体如在接下来的步骤中概述。 <img alt="图6" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig6highres.jpg" width="500" /> 图6。火焰取样光电离效率曲线为M / Z = 39和41的共振稳定基团炔丙基和llyl毫无疑问可基于所观测到的电离阈值的确定。 一旦异构体组合物是已知的，质谱中所采取的不同的光子能量和从火焰中的不同位置中，上述的协议部分描述的那样，以允许对各个物种的同分异构体特异性的摩尔分数分布的测定作为功能从燃烧器表面的距离。富烯和苯中从低压预混燃烧器的化学计量丙炔焰的代表摩尔分数分布示于图7中 22。对于每个火焰，通常总共40到50个独立的摩尔分数分布被确定为物种从M / Z = 1（氢原子），以M / Z = 78（苯和/或亚甲基环戊二烯），或者甚至更高，这取决于科学目标。这些摩尔分数分布，然后用来评估燃烧化学模型的预测能力，以及到validate他们。 <img alt="图7" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig7highres.jpg" width="500" /> 图7的实验摩尔分数进行访问。富烯和苯中从低压预混燃烧器的化学计量丙炔焰的名称。 一个典型的气溶胶质谱示于图8，它是从丙烷相对流扩散火焰内服用。观察到的物种，其中m / z比的范围从150到600，大约M / Z = 226的峰的离子信号。它超出了目前的实验能力，以确定所有的质谱或解开其可能形成的通路中观察到的物种。采取这种质谱作为距离的函数从所述燃料出口与上述（和在视频显示）提供了空间分辨的访问。一个国家代表sentative例子示于图8中的M / Z = 256（C 20 H 16）物种的入口。类似的配置文件可以用于任何其它物种，以及得到，这因而可以作为验证目标的任何燃烧反应模型。 <img alt="图8" fo:content-width="5in" src="/files/ftp_upload/51369/51369fig8highres.jpg" width="500" /> 从丙烷-O 2相流扩散火焰图8。火焰采样气溶胶质谱。入口示出了代表性的为C 20 H 16种在m / z = 256空间分辨的轮廓。

Watch this Scientific Journal Video about Flame Experiments at the Advanced Light Source: New Insights into Soot Formation Processes at JoVE.com

Flame Experiments at the Advanced Light Source: New Insights into Soot Formation Processes

从实验室规模的火焰与所有物种的质谱在线分析气体采样是一个功能强大的方法来研究在燃烧过程中产生的化学化合物的复杂混合物。再加上通过同步加速器产生的真空紫外辐射可调软电离，这种技术提供了同分异构体，解决了信息和潜在的片段 - 免费质谱。

火焰在实验的先进光源：全新洞察烟灰形成过程

The following experimental protocols and the accompanying video are concerned with the flame experiments that are performed at the Chemical Dynamics ...

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12.7K 次观看.  Sandia National Laboratories. 从实验室规模的火焰与所有物种的质谱在线分析气体采样是一个功能强大的方法来研究在燃烧过程中产生的化学化合物的复杂混合物。再加上通过同步加速器产生的真空紫外辐射可调软电离，这种技术提供了同分异构体，解决了信息和潜在的片段 - 免费质谱。 

视频: Flame Experiments at the Advanced Light Source: New Insights into Soot Formation Processes

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach.
The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles.
To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 &mu;m thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm2, which can be increased up to 17-18 mA/cm2 (~25% higher) after application of a simple diffuse back reflector made of a white paint.
To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23&deg;C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF2, and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF2, and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm2, up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.
Introduction
Light-trapping in silicon solar cells is commonly achieved via light scattering at textured interfaces. Scattered light travels through a cell at oblique angles for a longer distance and when such angles exceed the critical angle at the cell interfaces the light is permanently trapped in the cell by total internal reflection (Animation 1: Light-trapping). Although this scheme works well for most solar cells, there are developing technologies where ultra-thin Si layers are produced planar (e.g. layer-transfer technologies and epitaxial c-Si layers) 1 and or when such layers are not compatible with textures substrates (e.g. evaporated silicon) 2. For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3, silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.
Metal nanoparticles can effectively scatter incident light into a higher refractive index material, like silicon, due to the surface plasmon resonance effect 6. They also can be easily formed on the planar silicon cell surface thus offering a light-trapping approach alternative to texturing. For a nanoparticle located at the air-silicon interface the scattered light fraction coupled into silicon exceeds 95% and a large faction of that light is scattered at angles above critical providing nearly ideal light-trapping condition (Animation 2: Plasmons on NP). The resonance can be tuned to the wavelength region, which is most important for a particular cell material and design, by varying the nanoparticle average size, surface coverage and local dielectric environment 6,7. Theoretical design principles of plasmonic nanoparticle solar cells have been suggested 8. In practice, Ag nanoparticle array is an ideal light-trapping partner for poly-Si thin-film solar cells because most of these design principle are naturally met. The simplest way of forming nanoparticles by thermal annealing of a thin precursor Ag film results in a random array with a relatively wide size and shape distribution, which is particularly suitable for light-trapping because such an array has a wide resonance peak, covering the wavelength range of 700-900 nm, important for poly-Si solar cell performance. The nanoparticle array can only be located on the rear poly-Si cell surface thus avoiding destructive interference between incident and scattered light which occurs for front-located nanoparticles 9. Moreover, poly-Si thin-film cells do not requires a passivating layer and the flat base-shaped nanoparticles (that naturally result from thermal annealing of a metal film) can be directly placed on silicon further increases plasmonic scattering efficiency due to surface plasmon-polariton resonance 10.
The cell with the plasmonic nanoparticle array as described above can have a photocurrent about 28% higher than the original cell. However, the array still transmits a significant amount of light which escapes through the rear of the cell and does not contribute into the current. This loss can be mitigated by adding a rear reflector to allow catching transmitted light and re-directing it back to the cell. Providing sufficient distance between the reflector and the nanoparticles (a few hundred nanometers) the reflected light will then experience one more plasmonic scattering event while passing through the nanoparticle array on re-entering the cell and the reflector itself can be made diffuse - both effects further facilitating light scattering and hence light-trapping. Importantly, the Ag nanoparticles have to be encapsulated with an inert and low refractive index dielectric, like MgF2 or SiO2, from the rear reflector to avoid mechanical and chemical damage 7. Low refractive index for this cladding layer is required to maintain a high coupling fraction into silicon and larger scattering angles, which are ensured by the high optical contrast between the media on both sides of the nanoparticle, silicon and dielectric 6. The photocurrent of the plasmonic cell with the diffuse rear reflector can be up to 45% higher than the current of the original cell or up to 25% higher than the current of an equivalent cell with the diffuse reflector only.

Polycrystalline silicon thin-film solar cells on glass are fabricated by deposition of boron and phosphorous doped silicon layers followed by crystallisation, defect passivation and metallisation. Plasmonic light-trapping is introduced by forming Ag nanoparticles on the silicon cell surface capped with a diffused reflector resulting in ~45% photocurrent enhancement.

多晶硅薄膜太阳能电池电浆增强光捕获

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To ...

科研

工程学

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

在极低的温度下角分辨光电子能谱

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents and hence higher efficiencies. Photon up-conversion by way of triplet-triplet annihilation (TTA-UC) is an attractive technique for using these otherwise wasted low energy photons to produce photocurrent, while not interfering with the photoanodic performance in a deleterious manner. Further to this, TTA-UC has a number of features, distinct from other reported photon up-conversion technologies, which renders it particularly suitable for coupling with DSC technology. In this work, a proven high performance TTA-UC system, comprising a palladium porphyrin sensitizer and rubrene emitter, is combined with a high performance DSC (utilizing the organic dye D149) in an integrated device. The device shows an enhanced response to sub-bandgap light over the absorption range of the TTA-UC sub-unit resulting in the highest figure of merit for up-conversion assisted DSC performance to date.

An integrated device, incorporating a dye-sensitized solar cell and triplet-triplet annihilation up-conversion unit was produced, affording enhanced light harvesting, from a wider section of the solar spectrum. Under modest irradiation levels a significantly enhanced response to low energy photons was demonstrated, yielding a record figure of merit for dye-sensitized solar cells.

集成的三重态 - 三重态湮灭上转换系统，提高染料敏化太阳能电池的响应子带隙光

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

电池的使用同步为基础的硬X射线微断层故障分析

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is reported. The measurements were demonstrated at the 1-BM bending magnet beamline of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). By using a 2-D checkerboard &#960;/2 phase-shift grating, transverse coherence lengths were obtained along the vertical and horizontal directions as well as along the 45&#176; and 135&#176; directions to the horizontal direction. Following the technical details specified in this paper, interferograms were measured at different positions downstream of the phase grating along the beam propagation direction. Visibility values of each interferogram were extracted from analyzing harmonic peaks in its Fourier Transformed image. Consequently, the coherence length along each direction can be extracted from the evolution of visibility as a function of the grating-to-detector distance. The simultaneous measurement of coherence lengths in four directions helped identify the elliptical shape of the coherence area of the Gaussian-shaped X-ray source. The reported technique for multiple-direction coherence characterization is important for selecting the appropriate sample size and orientation as well as for correcting the partial coherence effects in coherence scattering experiments. This technique can also be applied for assessing coherence preserving capabilities of X-ray optics.

The measurement protocol and data analysis procedure are given for obtaining transverse coherence of a synchrotron radiation X-ray source along four directions simultaneously using a single 2-D checkerboard phase grating. This simple technique can be applied for complete transverse coherence characterization of X-ray sources and X-ray optics.

使用2-D棋盘相位光栅X射线束相干测量沿多个方向

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is ...

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

利用同步辐射微断层调查的多尺度三维微电子封装

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

散装异质结太阳能电池的印刷和制作<em&gt;原位</em&gt;形态特征

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

This protocol describes the operation of a liquid flow specimen holder for scanning transmission electron microscopy of AuNPs in water, as used for the observation of nanoscale dynamic processes.

使用扫描透射电子显微镜研究纳米大小的物体的动态过程中的液体

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a ...

Experimental Implementation of a New Composite Fabrication Method: Exposing Bare Fibers on the Composite Surface by the Soft Layer Method

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional component that should have high electrical conductivity, high mechanical properties, and high productivity.
In this regard, a carbon fiber/epoxy resin composite can be an ideal material to replace the conventional graphite bipolar plate, which often leads to the catastrophic failure of the entire system because of its inherent brittleness. Though the carbon/epoxy composite has high mechanical properties and is easy to manufacture, the electrical conductivity in the through-thickness direction is poor because of the resin-rich layer that forms on its surface. Therefore, an expanded graphite coating was adopted to solve the electrical conductivity issue. However, the expanded graphite coating not only increases the manufacturing costs but also has poor mechanical properties.
In this study, a method to expose fibers on the composite surface is demonstrated. There are currently many methods that can expose fibers by surface treatment after the fabrication of the composite. This new method, however, does not require surface treatment because the fibers are exposed during the manufacture of the composite. By exposing bare carbon fibers on the surface, the electrical conductivity and mechanical strength of the composite are increased drastically.

A protocol to expose bare fibers on the composite surface by eliminating resin rich area is presented. The fibers are exposed during fabrication of the composites, not by the post surface treatment. The exposed carbon composites exhibit high electrical conductivity in the through-thickness direction and high mechanical property.

一种新的复合制备方法的实验实现: 用软层法对复合材料表面裸露纤维进行曝光

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional ...

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.